Cypher syntax file asks about commentstring on open

Question

I am using syntax highlighting on my Cypher scripts from https://github.com/memgraph/cypher.vim. (I would open an issue there but the project and its predecessor haven't been touched in 3 years.) Works fine except when I create or load a .cypher file, or even switch to a .cypher buffer, the status bar gives

    commenstring=//%s
    commenstring=//%s
Press ENTER or type command to continue. 

which interrupts my workflow, especially since I change buffers a lot. As far as I can tell, comments are defined properly in the syntax file since they highlight correctly. But then again, I don't even know what this message is trying to tell me in order for me to know where to fix it. It's hardly an error, just a speedbump requiring an extra keypress.

Answer 1

But then again, I don't even know what this message is trying to tell me in order for me to know where to fix it

This line in ftplugin/cypher.vim is responsible for this:

let b:undo_ftplugin = 'setlocal commentstring'

https://github.com/memgraph/cypher.vim/blob/34280717f4a4bbc6adf09f3abd54a3e9f142adb3/ftplugin/cypher.vim#L14

Basically, undo_ftplugin should undo settings that filetype plugin sets when filetype is changed, to "be a good vim citizen". However in this case it has an error, instead of undoing commentstring it just calls an incomplete option local set, which effectively prints current option value.

It should be let b:undo_ftplugin = 'setlocal commentstring<'.

See :h undo_ftplugin